Ileal phosphorus digestibility of soybean meal for broiler chickens remains consistent across institutions in a collaborative study regardless of non-phytate phosphorus concentration in the pre-experimental starter diet

The same experimental protocol was used in 4 institutions to evaluate the impact of non-phytate phosphorus (nPP) concentration in the starter diet on regression method-derived ileal P digestibility of soybean meal (SBM) during the subsequent grower phase. A total of 1,536 Ross 308 male broiler chickens on d 0 post hatching were allotted to 2 pre-experimental starter diets that contained 3.5 or 4.5 g nPP/kg (96 replicate cages per diet, 8 birds per cage) for 18 d. Subsequently, 576 birds from each starter diet were selected and allocated to 3 experimental semi-purified grower diets containing 400, 510, or 620 g SBM/kg (32 replicate cages per diet, 6 birds per cage) for 3 d until collection of ileal digesta. Statistical analysis was conducted as a randomized complete block design with the starter period as whole plot and the grower period as split-plot. The only significant 2-way interaction was between grower diet and experimental institution (P < 0.05) on BW gain and gain to feed ratio. The main effect of institution and grower diet impacted (P < 0.05) feed intake, the digestibility of DM, P, and calcium, and disappearance of inositol hexakisphosphate (InsP6) in the grower diets. Birds fed the 3.5 g nPP/kg starter diet had lower (P < 0.05) BW gain and feed intake during the grower period, but presented higher (P < 0.05) digestibility of P and disappearance of InsP6 compared with the birds that were fed the 4.5 g nPP/kg starter diet. Regression method-derived ileal P digestibility of SBM was determined to be 46 or 42% for the respective 3.5 or 4.5 g nPP/kg pre-experimental starter diet and was not affected by the nPP concentration or by the institution. In conclusion, the experimental protocol used in the current study resulted in similar estimates across multiple institutions and is thus endorsed for future application in studies that aim to expand the database of digestible P content in plant source feed ingredients.

Comparison of different protein sources on the phosphorus digestibility of soybean meal for broiler chickens determined using the regression method

A study was conducted to evaluate the P digestibility in soybean meal (SBM) using the regression method with different basal diet that varied in protein sources. The treatments were organized in a 4 × 3 factorial arrangement, where 4 semipurified diets were formulated with varying source of protein (no protein supplement, or added casein, potato protein isolate (PPI), or dried egg albumen (DEA) at 60 g/kg) and 3 dietary levels of SBM (290, 370, or 450 g/kg). The study was a randomized complete block design with 8 replicate cages of 6 birds per cage. The experimental diets were fed from d 19 to 22 posthatching, excreta samples were collected from d 20 to 22, and ileal digesta samples were collected on d 22. Data were analyzed as a 2-way ANOVA using the GLM procedure. The digestibility and total tract utilization of DM, P, Ca, and N were affected by protein source (P < 0.05). Diets with casein presented the highest (P < 0.05) digestibility of N. Increasing SBM level in all dietary protein sources reduced (P < 0.001) the digestibility and total tract utilization of DM. The regression-derived ileal digestibility of P in SBM was 57.8 (SE = 3.78), 63.2 (SE = 5.02), 58.8 (SE = 4.53), and 35.3% (SE = 5.27) for diets without protein supplement, with casein, PPI, or DEA, respectively; the corresponding P retention were 52.2 (SE = 11.09), 83.4 (SE = 14.89), 42.6 (SE = 15.88), and 51.9% (SE = 14.67). The protein source affected (P < 0.05) the slope and intercept of P digestibility in SBM. A comparison of the coefficients using confidence intervals demonstrated that the ileal digestibility of P in SBM determined in diets with DEA was lower (P < 0.05) than the other protein sources, which did not differ from one another. These results indicate that the selection of dietary protein supplements may affect P digestibility assays using the regression method.

A new insight in immunomodulatory impact of botanicals in treating avian coccidiosis

Avian coccidiosis is caused by genus Eimeria (E.) i.e. E. maxima, E. necatrix, E. tenella, E. acervulina, E. brunette and E. mitis and lead to three billion US dollar per year economic loss in poultry industry and reduces the growth performance of birds. To purge undesirable foreign agents, immune system produces a variety of molecules and cells that ultimately neutralize target particles in healthy organisms. However; when this particular system compromises, infection develops and the load of pathogens along with their virulence factors overcome both; innate and adaptive immune systems. Livestock and poultry sectors are important part of agriculture industry worldwide. Due to excessive use of chemotherapeutic agents, pathogens have developed resistance against these agents leading to the great economic losses. Numerous therapeutic approaches are in routine process for the treatment and prevention of various ailments but irrational use of antibiotics/chemicals has raised alarming concerns, like the development of drug resistant strains, residual effects in ultimate users and environmental pollution. These problems have led to the development of alternatives. In this regard, anticoccidial vaccine can be used as an alternative but due to high cost of production, plant derived biological response modifiers and antioxidants compounds are considered as a promising alternative. This review summarizes the immunotherapeutic effects of different compounds particularly with reference to avian coccidiosis.

Validation of a 3-point model for the determination of energy values using the regression method in broiler chickens

Two experiments (Exp.) were conducted to validate a 3-point model for the regression method of determining ME, using canola meal (CM) and wheat as test ingredients (TI). Corn-soybean meal-based test diets (TD) contained 0, 100, 200, or 300 g/kg CM, added at the proportional expense of all energy contributing ingredients for Exp. 1, and 0, 150, 300, or 450 g/kg wheat for Exp. 2. For each Exp., 192 Cobb 500 male broiler chickens were weighed and allotted by BW to 1 of 4 treatments at d 21 post hatching in a randomized complete block design. Growth performance and metabolizability responses were evaluated for linear and quadratic effects using orthogonal contrasts, and ileal digestible energy (IDE), ME, and MEn of TI were determined by regressing the TI-associated energy against the dry matter intake of TI using a generalized linear model. Four data sets were used to determine ME, using all possible 3 and 4-point combinations of TD in each Exp. Increasing TI inclusion elicited linear decreases (P < 0.01) in the digestibility and metabolizability of DM and GE in the 2 studies. The ME of CM obtained from the 4 data sets ranged from 1,731 to 1,992 kcal/kg DM, however, excluding the highest concentration of CM produced the highest estimate of ME, whereas the other 3 sets ranged from 1,731 to 1,793 kcal/kg DM. The ME of wheat from the 4 data sets had a smaller range of 3,041 to 3,106 kcal/kg DM. Excluding the highest concentration of either TI produced higher standard errors for the estimate of ME compared to the other 3 sets (42 and 36% greater SE, respectively). Results for IDE and MEn were similar. These data indicate that there is no difference in the variation of estimates between the 3 and 4-point models, provided that the inclusion of the TI is adequate and both models represent the linearity and variability of responses.

Regression-derived phosphorus digestibility responses of broiler chickens to heat treatment of soybean meal and poultry meal

Two studies were conducted to evaluate the effects of autoclaving soybean meal (SBM) or poultry meal (PM) on their respective regression-derived phosphorus (P) ileal digestibility and utilization coefficients. On day 19 post hatching 384 or 320 Cobb 500 male broiler chickens were individually weighed and allotted into 6 or 5 treatments in Experiment 1 or 2, respectively. Both experiments consisted of 8 replicate cages with 8 birds per cage in a randomized complete block design. In the first study, 6 diets were formulated with either non-autoclaved or autoclaved soybean meal at 380, 480, or 580 g/kg in a 2 × 3 factorial. The second consisted of 5 diets including one corn-soybean meal and cornstarch based basal diet and 4 diets with 40 or 80 g/kg of non-autoclaved PM or autoclaved PM (APM). Chromic oxide was added as an indigestible index to determine the ileal digestibility and retention of nutrients. Birds received the experimental diets for 3 d and excreta collection was conducted during the last 2 d. At the end of the experiments all birds were euthanized by CO₂ asphyxiation and ileal digesta samples were collected. Data were analyzed by ANOVA using the GLM procedure. In both studies autoclaving decreased (P < 0.05) DM digestibility and retention. Increasing the inclusion level of test ingredients caused a linear increase (P < 0.05) in intake of digestible and utilizable P in both studies, and linear reductions in the digestibility and retention of DM and P in the soybean meal study. Inclusion of autoclaved SBM resulted in higher (P < 0.01) ileal digestibility of P and retention of P and Ca. The estimated ileal digestibility of P in SBM, autoclaved SBM, PM and APM were 45, 53.6, 61.2, and 61.2%, respectively, the corresponding retention were 40.6, 45, 51.7, and 59.2%, respectively. Comparison of the regression coefficients revealed that autoclaved SBM tended (P = 0.058) to have higher P digestibility than non-autoclaved while no effect was noted with PM.

Effects of feeding solid-state fermented wheat bran on growth performance and nutrient digestibility in broiler chickens

Solid-state fermentation has been used to improve the nutritive value of feed ingredients. In the present study, we investigated the effects of solid-state fermented wheat bran (FWB) on growth performance and apparent digestibility in broiler chickens. We measured the growth performance (ADFI, ADG, feed conversion, livability, and European performance efficiency factor) over 38 d in chicks fed a corn-soybean meal control diet (CON) or CON plus wet FWB (25 g/kg [T₁]; 50 g/kg [T₂]); or T₁ plus 3 g/kg (T₃); or T₂ plus 6 g/kg (T₄) soybean oil). The same diets were used to determine nutrient availability in chicks aged 20 d. Regression equations for AME and AME_n were obtained using 20-day-old chicks fed either the corn-soybean meal basal diet only or basal diet partially substituted with 50, 150, or 300 g/kg DM FWB. Diets containing 25 or 50 g/kg wet FBW did not affect the growth performance of broiler chickens, nor the apparent DM, energy, and nitrogen digestibility of the feeds, compared with the control diets (all P > 0.05). Further supplementation with oil did not improve the growth performance of broiler chickens compared with controls or chickens fed FBW. However, chickens fed diets containing soybean oil (T₃ or T₄) had lower (P = 0.005 and P = 0.040, respectively) apparent DM and energy digestibility than the control and FWB groups. The regression equations for AME and AME_n with the substitution of FWB produced values of 1,854.3 and 1,743.9 kcal/kg DM, respectively, and the equations were Y = 1854.3X + 52.7 (R² = 0.971, n = 24, P < 0.001), and Y = 1743.9X + 44.6 (R² = 0.978, n = 24, P < 0.001), respectively. Supplementation with wet FWB did not affect the growth performance of broiler chickens. Therefore, FWB is a suitable feed component for broilers.

Energy value of dry fat and stabilised rice bran for broiler chickens

1. The ileal digestible energy (IDE), metabolisable energy (ME) and nitrogen-corrected ME (MEn) of dry fat (DF) and stabilised rice bran (SRB) were determined in two experiments with broiler chickens using the regression method.2. Chickens were fed a common broiler starter diet from d 0 to 17 and experimental diets from d 17 to 22 post hatching. Three diets were prepared; a maize-soybean meal reference diet (RD) and two test diets containing either DF at 50 or 100 g/kg replacement (Experiment 1) or SRB at 100 or 200 g/kg replacement (Experiment 2) of the energy-contributing ingredients in the RD. In each experiment, 192 chickens were randomly allocated to one of three dietary treatments in a randomised complete block design, comprising eight replicate cages with eight birds per cage.3. In Experiment 1, the IDE, ME and MEn linearly increased (P < 0.001) with increasing DF concentrations, while in Experiment 2, the IDE, ME and MEn of the diets were not affected by dietary supplemental SRB. The regression-derived IDE concentration for DF and SRB were 25.30 and 14.88 MJ/kg DM, respectively. The respective ME and MEn estimates (MJ/kg DM) were 25.32 and 24.78 for DF; 14.38 and 13.36 for SRB.4. In conclusion, the current data showed that broiler chickens utilised between 77% and 79% and 68% to 76% of the gross energy (GE) in DF and SRB, respectively, and this suggested a strong potential for these ingredients as dietary energy sources for broiler chickens.

Tryptophan in poultry nutrition: Impacts and mechanisms of action

Many studies have shown that productivity, immune system, antioxidant status, and meat and egg quality can be optimized by dietary supplementation with amino acids that are not usually added to poultry diets. Understanding the effects of these amino acids may encourage feed manufacturers and poultry producers to include them as additives. One of these amino acids is tryptophan (Trp). The importance of Trp is directly related to its role in protein anabolism and indirectly related to its metabolites such as serotonin and melatonin. Thus, Trp could affect the secretion of hormones, development of immune organs, meat and egg production, and meat and egg quality in poultry raised under controlled or stressed conditions. Therefore, this review discusses the main roles of Trp in poultry production and its mode (s) of action in order to help poultry producers decide whether they need to add Trp to poultry diets. Further areas of research are also identified to address information gaps.

Effects of dietary barley inclusion and glucanase supplementation on the production performance, egg quality and digestive functions in laying ducks

This study evaluated the effects of barley inclusion and glucanase supplementation on the productive performance and digestive function in laying ducks. The experiment used a randomized design with a 5 × 2 factorial arrangement of 5 graded levels of barley (0%, 15%, 30%, 45% and 60%) with or without 1.5 g/kg β-1,3-1,4-glucanase (15,000 U/kg). During the experimental period of 120 d, the weight and total number of eggs within each pen were recorded daily, and egg quality was determined every 4 wk. At the end of the experiment, 3 randomly selected ducks within each replicate were sacrificed, then duodenal digesta and jejunal mucosa was collected. Dietary inclusion of barley had no effects on egg production, daily egg mass or FCR, but supplementation with glucanase improved egg production and FCR (P < 0.01). Barley did not affect feed intake of laying ducks, but glucanase tended to increase feed intake (P = 0.09). Neither barley nor β-glucanase had effects on the egg quality variables, except for yolk color score, which was decreased with increasing barley supplementation. Glucanase, but not barley, increased the activity of chymotrypsin and amylase in duodenal digesta. Barley inclusion affected the activity of alkaline phosphatase and maltase in jejunal mucosa (P < 0.05), but β-glucanase had no effects on the activity of these brush border enzymes. Barley inclusion increased the glucan content in duodenal digesta, but supplementation of glucanase to barley-based diet reduced digesta glucan content and reduced total volatile fatty acids and increased the proportion of acetic acid in cecal contents. The results indicate that, without glucanase, the optimal dietary barley level in the diets of laying ducks is about 13% for maximal production performance; glucanase supplementation of the barley diets improved production performance, probably through enhancing digestive function.

Coccidia Vaccine Challenge and Exogenous Enzyme Supplementation in Broiler Chicken 1. Effect on Digesta Viscosity, Diet Energy Utilization, and Apparent Metabolizable Energy Value of Wheat

This study examined the effect of exogenous mixed-enzyme supplementation (xylanase, β-glucanase, and pectinase) to a corn-SBM (CS) and a wheat-CS-based (WCS) diet in birds challenged with coccidia vaccine (Coccivac B-52™). The WCS-based diet was produced by replacing 30% of the energy-yielding portions of the CS-based diet with wheat. On day 14, 448 (n = 7) Cobb by-product breeder male broilers were assigned to a 2 (diet types) × 2 (with or without enzyme supplementation) × 2 (0 or 20 × coccidia vaccine challenge; CVC) factorial arrangement of treatments in a completely randomized design for the determination of the apparent metabolizable energy (AME) value of wheat. Treatment effects on jejunum digesta viscosity and AME corrected for nitrogen (AMEn) of the diets were evaluated within each diet type as a 2 × 2 factorial arrangement of treatments, 7- and 14-day post-challenge. Seven-day post-challenge (day 21), dry matter (DM) and energy utilization, AME, and AMEn of the CS- and WCS-based diets decreased (p < 0.05) with CVC. Both AME and AMEn of wheat decreased (p < 0.05) by about a 20% in CVC-birds 7-day post-challenge. Enzyme and CVC resulted in a decrease (p < 0.05) in jejunal digesta viscosity in birds fed the CS-based diets, while there was an interaction (p < 0.05) between CVC and enzyme, with enzyme lowering (p < 0.05) the viscosity of digesta 7-day post-challenge. Results from this study showed that CVC resulted in a 20% decrease in AMEn 7-day post-challenge, while the interaction between exogenous enzyme supplementation and CVC resulted in an improvement in nitrogen utilization (~6%) in CVC birds fed the corn-SBM-based diet 7-days post challenge.

Energy values of copra meal and cornstarch for broiler chickens

Two studies were conducted with broiler chickens to determine the ileal digestible energy (IDE), ME, and MEn in copra meal (CM) and cornstarch using the regression method. On day 15 and 16 for experiments 1 and 2, respectively, 192 male birds were individually weighed and allotted into 3 dietary treatments with 8 replicate cages and 8 birds per cage in a randomized complete block design with the BW as a blocking factor in each experiment. Dietary treatments consisted of 3 inclusion levels of test ingredients (i.e., 0, 100, or 200 g/kg) in corn-soybean meal-based diets using CM or cornstarch as test ingredients for experiment 1 or 2, respectively. Titanium dioxide was added as an indigestible marker to determine the ileal digestibility and utilization of energy by the index method. Experiments lasted 5 d, and excreta collection was conducted during the last 3 d of each experiment. At the end of experiments, birds were euthanized by CO2 asphyxiation, and ileal digesta samples were collected. Data were analyzed by the ANOVA using the GLM procedure. In experiment 1, the apparent ileal digestibility (AID) of DM and gross energy (GE) and IDE in test diets linearly decreased (P < 0.05) with substitution of CM in test diets. In experiment 2, there were quadratic increases (P < 0.01) in the AID of DM and GE and IDE in diets as the concentration of cornstarch in test diets increased. In addition, linear increases (P < 0.05) in the apparent total tract utilization of DM, N, and GE and ME and MEn in test diets were observed. The estimates of IDE, ME, and MEn in CM were 2,493, 3,727, and 3,546 kcal/kg DM, respectively, whereas respective values of cornstarch were estimated at 4,181, 3,992, and 3,946 kcal/kg DM, respectively. In conclusion, inclusion of CM in diets may reduce the digestibility of GE, whereas the digestibility and utilization of GE may increase when adding cornstarch into diets for broiler chickens.

Energy value of rice, broken rice, and rice bran for broiler chickens by the regression method

The objective of this study was to determine the ileal digestible energy (IDE), ME, and ME_n of rice, broken rice, and rice bran. The birds were fed a standard starter diet from day 0 to 14 and experimental diets from day 15 to 21 after hatching. A total of 336 birds were grouped by BW and assigned to 7 diets, each diet comprised 8 replicates with 6 birds per replicate. The diets comprised a reference diet (RD) and 6 test diets (TD). The TD contained 2 levels of rice, broken rice or rice bran that partly replaced the energy sources in the RD at 120 or 240 g/kg (rice and broken rice) or 150 or 300 g/kg (rice bran). Addition of rice or broken rice to RD linearly increased (P < 0.01) ileal digestibility of DM, energy, as well as total tract metabolizability of DM, energy, and N-corrected energy in the TD. The inclusion of rice bran in the TD linearly decreased (P < 0.01) energy digestibility and utilization in the test diet. Regressions of rice-associated, broken rice-associated, or rice bran-associated IDE, ME, or ME_n intake in kcal against rice, broken rice, or rice bran intake were as follows: IDE = Y = 2 (6) + 3,185 (73) × Rice + 3,199 (72) × Broken Rice + 2,562 (61) × Rice Bran, r2 = 0.98; ME = Y = 8 (6) + 3,103 (72) × Rice + 3,190 (71) × Broken Rice + 2,709 (60) × Rice Bran, r2 = 0.98; ME_n = Y = 4 (5) + 3,014 (68) × Rice + 3,092 (101) × Broken Rice + 2,624 (57) × Rice Bran, r2 = 0.98; Based on the regression equations, the IDE, ME, ME_n values (kcal/kg of DM) of rice were 3,185, 3,103 and 3,014, respectively, while for broken rice, the values were 3,199, 3,190, and 3,092 and for rice bran, the values were 2,562, 2,709, and 2,624, respectively.

Energy values of triticale or sorghum distillers' dried grains with solubles and rye fed to broiler chickens

The current experiments were conducted to determine ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (MEn) of triticale distillers' dried grains with solubles (TDDGS), sorghum distillers' dried grains with solubles (SDDGS), or rye for broiler chickens using the regression method. Five diets including a corn-soybean meal reference diet and four assay diets, prepared by adding TDDGS or SDDGS at 10% or 20% of the diet to partly replace energy-yielding ingredients in the reference diet, were used. Each of the five diets was fed to eight replicate cages of six birds per replicate cage from day 14 to 21 post-hatching. Similarly in experiment 2, corn-soybean reference diet and two assay diets in which rye at 20% or 40% replaced energy-yielding sources in the reference diet and each of the three diets was fed to eight replicate cages of eight birds per replicate cage from day 18 to 23 post-hatching. Excreta samples were collected twice daily from day 18 to 20 in experiment 1 or day 20 to 22 in experiment 2, and ileal digesta were collected on day 21 (experiment 1) or day 23 (experiment 2). The IDE, ME, and MEn (kcal/kg DM) of TDDGS or SDDGS were derived from the regressions of TDDGS-, SDDGS-, or rye-associated, IDE, apparent ME, and apparent MEn intake in kilocalories against the intake of TDDGS, SDDGS, or rye (X, kg DM), respectively. For diets with TDDGS substitution, regression equations were IDE = 12.3 + 3,288X, ME = -3.0 + 2,800X, and MEn = -0.4 + 2,647X. The equations for the SDDGS diets were IDE = -4.8 + 3,247X, ME = -7.6 + 3,210X, and MEn = -7.0 + 3,072X; and those for the rye diets were IDE = 9.5 + 3,002X, ME = 6.3 + 3,053X, and MEn = 4.8 + 2,928X. The IDE contents did not differ between TDDGS and SDDGS whereas the ME and MEn contents were greater (P < 0.05) in the SDDGS than in the TDDGS. In conclusion, the current study provided energy values of the DDGS sources and rye using the regression method. The regression-derived IDE for TDDGS, SDDGS, or rye were 3,288, 3,247, or 3,002 kcal/kg DM, respectively; corresponding ME were 2,800, 3,210, or 3,053 kcal/kg DM. The respective regression-derived MEn for TDDGS, SDDGS, or rye were 2,647, 3,072, or 2,928 kcal/kg DM for broiler chickens.

Effects of a combination of xylanase, amylase and protease, and probiotics on major nutrients including amino acids and non-starch polysaccharides utilization in broilers fed different level of fibers

This study evaluated the effects of a combination of xylanase, amylase, and protease (XAP), with probiotics (3 Bacillus spp.) supplementation on apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients in Cobb 500 broilers from 0 to 21 d. A completely randomized 2 × 4 factorial design (2 levels of fiber; 4 types of supplements) with 8 replicate cages (6 birds/cage) was used. Each low and high-fiber diet contained 500 FTU/kg Buttiauxella sp. phytase and was supplemented with: (a) none (control), (b) XAP (2,000 U xylanase + 200 U amylase + 4,000 U protease/kg diet), (c) probiotics (75,000 CFU/g of Bacillus spp.), or (d) XAP + probiotics. High fiber decreased (P < 0.05) nitrogen-corrected apparent metabolizable energy (AMEn), AID of all amino acids (AA), AID and ATTD of dry matter (DM), crude protein (CP), starch, and gross energy (GE). High fiber increased (P < 0.01) the flow of total non-starch polysaccharides (NSP) in both ileum and total tract. The XAP + probiotics increased (P < 0.01) AMEn as well as AID and ATTD of DM, CP, GE, starch, while alone, XAP yielded similar improvement except for DM compared with control. The supplemental XAP alone improved (P < 0.01) the digestibility of most of the AAs compared with control. Moreover, XAP + probiotics increased (P < 0.05) AID of all AA except arginine and serine compared with control. A fiber × supplements interaction (P < 0.05) was found for AID of histidine and threonine, and their digestibility in high-fiber diet was improved to a level comparable to low-fiber diet by XAP + probiotics. The flow of NSP in XAP group was 5 to 6% lower than in control while NSP flow in XAP + probiotic group was further 4% lower than that of XAP group (P < 0.01). The results infer that the combination of XAP and probiotics can effectively optimize the nutrient digestibility in broilers fed both low and high-fiber diets.

Historical flaws in bioassays used to generate metabolizable energy values for poultry feed formulation: a critical review

Dietary energy available to animals is key for formulating feed as it is required for all aspects of the animal's life. In poultry, apparent (AME) and true (TME) metabolizable energy (ME) values have been used for feed formulation with (AMEn or TMEn) or without correction for nitrogen balance. For the past 50 yr, the accuracy of ME has been an ongoing debate, and the comparability of data produced using different bioassay systems is often questionable. Overall, the ingredient matric ME values used in feed formulation are not consistent, and to some extent, confusing. This review was to examine ME data published in the past century to elucidate the accuracy of different bioassay systems and examine the values for accuracy and useability. A variety of flaws are identified in the literature, suggesting a thorough re-thinking of feedstuff ME values currently used in feed formulation and in developing prediction equations. Two protocols, namely multiple linear regression and basal diet substitution methods, are proposed as more accurate bioassays for feedstuff ME values. AME aligns more closely with the actual energy levels of feed ingredients likely available to growing birds, which should be used for poultry feed formulations instead of AMEn. It is suggested that nutritionists need to carefully apply any reported AME values and only use those in formulation practice after careful scrutinizing. Any in vitro, NIR or table values must be calibrated or computed based on the values produced from flawless bioassays so as to apply the derived values accurately. Flaws identified in this literature review can be avoided with care to achieve more accurate AME. However, the assumption that the energy of individual ingredients is additive in a complete diet is still untrue at least under some circumstances. This may require efforts from industry and researchers to investigate relations among the main ingredients in a complete diet so that more accurate formulation can be performed based on the outcomes that may fine-tune the additivity assumption.

Influence of inclusion level of barley in wheat-based diets and supplementation of carbohydrase on growth performance, nutrient utilisation and gut morphometry in broiler starters

1. The influence of barley inclusion level and supplementation of a multi-component non-starch polysaccharide degrading enzyme on performance and nutrient utilisation in broilers was investigated. Normal-starch hulled barley was evaluated with five levels of inclusion (0, 141, 283, 424 and 565 g/kg) in a wheat-based diet and two levels of enzyme supplementation (0 and 150 g/tonne of feed; a 5 × 2 factorial arrangement of 10 dietary treatments). All diets were equivalent in metabolisable energy and digestible amino acid contents. A total of 400, one-d old male broilers (five cages/treatment; eight birds/cage) were used in the experiment.2. Regardless of enzyme supplementation, weight gain (WG) increased up to 283 g/kg of barley and was reduced afterwards (P < 0.01). Increasing levels of barley resulted in greater (P < 0.001) gain per feed (G/F). Enzyme addition increased WG (P < 0.05) and G/F (P < 0.001) at each barley inclusion level.3. Birds fed diets with 0 and 565 g/kg barley showed the lowest and highest (P < 0.001to 0.05) digestibility for all nutrients measured, respectively. Digestibility of all nutrients was improved by enzyme supplementation at each barley inclusion level (P < 0.05). The nitrogen-corrected apparent metabolisable energy improved with increasing inclusion of barley (P < 0.001) and supplemental enzyme (P < 0.01). Increasing inclusion of barley increased the relative weight of gizzard (P < 0.001) and reduced jejunal digesta viscosity (P < 0.001). Supplemental enzyme (P < 0.001) reduced digesta viscosity.4. The optimum inclusion level of barley, with respect to growth performance, was 283 g/kg of diet. Increasing barley inclusion improved nutrient and energy utilisation, possibly through lowered digesta viscosity and better function of the gizzard. Feed efficiency and nutrient and energy utilisation can benefit from carbohydrase supplementation in barley-based diets, regardless of barley inclusion level.

Energy values of solvent-extracted canola meal and expeller-derived canola meal for broiler chickens and growing pigs determined using the regression method1

The energy values of solvent-extracted canola meal (SECM) and expeller-derived canola meal (EDCM) for broiler chickens and growing pigs were determined in 2 experiments using the regression method. Corn-soybean meal reference diet (RF) and 4 test diets were prepared. The test diets consisted of SECM or EDCM that partly replaced the energy sources in the RF at 100 or 200 g/kg, respectively. The ratios of all energy ingredients were kept similar across all experimental diets. In Exp. 1, a total of 300 birds were fed standard broiler starter diet from days 0 to 19 posthatching. On day 19, 240 birds (776 ± 79.3 g initial BW) were assigned into 5 experimental diets in a randomized complex block design with BW as a blocking factor. Excreta were collected from days 23 to 25 and ileal digesta were collected after birds were euthanized by CO2 asphyxiation on day 26. In Exp. 2, 40 barrows (28.4 ± 1.6 kg initial BW) were allotted to 5 experimental diets according to the randomized complete block design with BW as a blocking factor. After 5-d adaption period, the feces and urine samples were collected for 5 d by total collection method. The ileal digestible energy (IDE), apparent ME (AME), and nitrogen-corrected apparent ME (AMEn) in Exp. 1 and the DE, AME, and AMEn in Exp. 2 for experimental diets and canola meals were determined. In Exp. 1, the inclusion of canola meals to RF linearly decreased the IDE, AME, and AMEn for birds fed SECM diets (P < 0.01) and the AME and AMEn for birds fed EDCM diets (P < 0.01). Furthermore, quadratic effects were also found in the IDE, AME, and AMEn by the inclusion of EDCM to RF (P < 0.05). The IDE were 2,194 and 3,514 kcal/kg DM for SECM and EDCM in broiler chickens, respectively. The respective ME and MEn values were 1,919 and 1,695 kcal/kg DM for SECM and 3,134 and 2,937 kcal/kg DM for EDCM. In Exp. 2, the SECM or EDCM addition to RF linearly decreased the AME and AMEn for pigs (P < 0.01). The DE content was also decreased linearly with the increasing level of SECM (P < 0.01). The DE, ME, and MEn of SECM for pigs were 3,109, 2,891, and 2,655 kcal/kg DM, respectively. The EDCM contained 3,850 kcal of DE, 3,581 kcal of ME, and 3,491 kcal of MEn/kg DM for pigs. In conclusion, the energy values of EDCM are greater than those of SECM for broiler chickens and pigs, and pigs utilize more of the GE in SECM and EDCM than broiler chickens.

Energy Concentration and Phosphorus Digestibility in Hatchery Byproducts Fed to Nursery Pigs

Simple Summary

There is limited information on nutritional value of hatchery byproducts as a swine feed ingredient. The objective of this study was to determine energy concentrations and phosphorus digestibility of hatchery byproducts fed to nursery pigs. Test ingredients were infertile eggs, unhatched eggs, culled chicks, and a mixture of the three. Culled chicks had the greatest energy concentrations, whereas infertile eggs had the lowest values. The standardized total tract digestibility of phosphorus in infertile eggs was greater than that in unhatched eggs, culled chicks, and the mixture. Based on the current results, feed formulation would be possible when using hatchery byproducts in swine diets.

Abstract

The objective was to measure energy concentrations and standardized total tract digestibility (STTD) of phosphorus (P) in hatchery byproducts. In Experiment 1, 20 nursery barrows were used to measure energy concentrations in hatchery byproducts. A basal diet based on corn and dried whey and four additional diets containing 25% of infertile eggs, unhatched eggs, culled chicks, or a mixture of the three hatchery byproducts were prepared. In Experiment 2, the STTD of P was measured using 20 nursery barrows. Four diets containing 25% of the same hatchery byproducts used in Experiment 1 as the sole source of P were prepared, and a P-free diet was prepared to measure basal endogenous losses of P. The marker-to-marker method was employed for total collection. Metabolizable energy in culled chicks was the greatest (4560 kcal/kg as-is basis; p < 0.05), whereas infertile eggs had the lowest value (2645 kcal/kg as-is basis; p < 0.05). The STTD of P in infertile eggs (81.7%) was greater than that in unhatched eggs, culled chicks, and the mixture (61.6, 53.9, and 47.4%, respectively; p < 0.05). In conclusion, culled chicks had the greatest metabolizable energy and infertile eggs had the greatest phosphorus digestibility among the test ingredients.

Estimation of metabolisable energy and net energy of rice straw and wheat straw for beef cattle by indirect calorimetry

Two experiments were conducted to estimate the metabolisable energy (ME) and net energy (NE) of rice straw and wheat straw for beef cattle. In each experiment, 16 Wandong bulls (Chinese indigenous yellow cattle) were assigned to 4 dietary treatments in a completely randomised design. Four dietary treatments included one corn silage-concentrate basal diet and three test diets in which the basal diet was partly substituted by rice straw (Exp. 1) or wheat straw (Exp. 2) at 100, 300 and 600 g/kg. Total collection of faeces and urine was conducted for 5 consecutive days after a 2-week adaption period, followed by a 4-d period where gas exchange measurements were measured by an open-circuit respiratory cage. Linear regression equations of rice straw- or wheat straw-associated ME and NE contribution in test diets against rice straw or wheat straw substitution amount were developed to predict the ME and NE values of rice straw and wheat straw. These regression equations resulted in ME and NE values (dry matter basis) of 6.76 and 3.42 MJ/kg for rice straw and 6.43 and 3.28 MJ/kg for wheat straw, respectively. The NE and ME requirement for maintenance of Wandong cattle fed a straw-based diet were 357 and 562 kJ·kg^-0.75·d^-1, respectively. The regression-derived ME and NE have lower standard errors and coefficients of variation than those estimated by any single substitution ratio. Our study found that the regression method based on multiple point substitution is more reliable than the substitution method for energy evaluation of feedstuffs for beef cattle.

Techniques for evaluating digestibility of energy, amino acids, phosphorus, and calcium in feed ingredients for pigs

Sound feed formulation is dependent upon precise evaluation of energy and nutrients values in feed ingredients. Hence the methodology to determine the digestibility of energy and nutrients in feedstuffs should be chosen carefully before conducting experiments. The direct and difference procedures are widely used to determine the digestibility of energy and nutrients in feedstuffs. The direct procedure is normally considered when the test feedstuff can be formulated as the sole source of the component of interest in the test diet. However, in some cases where test ingredients can only be formulated to replace a portion of the basal diet to provide the component of interest, the difference procedure can be applied to get equally robust values. Based on components of interest, ileal digesta or feces can be collected, and different sample collection processes can be used. For example, for amino acids (AA), to avoid the interference of fermentation in the hind gut, ileal digesta samples are collected to determine the ileal digestibility and simple T-cannula and index method are commonly used techniques for AA digestibility analysis. For energy, phosphorus, and calcium, normally fecal samples will be collected to determine the total tract digestibility, and therefore the total collection method is recommended to obtain more accurate estimates. Concerns with the use of apparent digestibility values include different estimated values from different inclusion level and non-additivity in mixtures of feed ingredients. These concerns can be overcome by using standardized digestibility, or true digestibility, by correcting endogenous losses of components from apparent digestibility values. In this review, methodologies used to determine energy and nutrients digestibility in pigs are discussed. It is suggested that the methodology should be carefully selected based on the component of interest, feed ingredients, and available experimental facilities.

Exogenous protease supplementation of poultry by-product meal-based diets for broilers: Effects on growth, carcass characteristics and nutrient digestibility

An experiment was conducted to investigate the effects of three levels (0%, 3% and 6%) of poultry by-product meal (PBM) with or without protease on broiler growth, carcass characteristics and nutrient digestibility from 1 to 35 days. Two hundred and forty birds (n = 240) were fed equi-caloric and equi-nitrogenous (ME 2850 kcal/kg; CP 20%) diets throughout the experiment. The enzyme supplementation increased feed intake (p < .01) and body weight gain (p < .01), but feed:gain remained unaffected (p > .05) from 1 to 21 days. Increasing level of PBM decreased feed intake (p < .05), but body weight gain was improved (p < .05) at 3% PBM level during 1 to 21 days. The feed:gain was improved (p < .05) in birds fed diets containing 3% PBM. The feed:gain was also improved in birds fed diets containing 3% PBM from 1 to 35 days. However, feed intake and body weight gain in birds fed diets containing PBM remained unaffected. An interaction (p < .01) on feed intake between enzyme and PBM was noticed during 1 to 21 days. However, no interaction was recorded for body weight gain and feed:gain. The per cent carcass yield improved (p < .01) in birds fed diets supplemented with enzyme. The per cent breast meat yield was depressed (p < .005) in birds fed diets containing PBM. Apparent metabolizable energy (p < .001), nitrogen retention (p < .01), apparent metabolizable energy corrected for nitrogen (p < .001), and apparent digestibility coefficient for nitrogen (p < .01) improved in birds fed diets containing enzyme; however, a reverse was noticed in those fed diets containing only PBM. In conclusion, inclusion of 3% PBM along with supplementation of exogenous protease improved performance and nutrient digestibility in broilers.

Palatability, digestibility, and metabolizable energy of dietary glycerol in adult cats

Glycerol is a humectant, which reduces water activity when added to the diet. This property seems to offer dietary benefits, specifically in high-moisture diets for cats, where some humectants cannot be used. According to the U.S. Food and Drug Administration, glycerol is generally recognized as sustenance safe (GRAS). It is suggested that cats are able to metabolize glycerol and use it as an energy source without compromising health. Three experiments were conducted to evaluate the following characteristics of glycerol in the diet for cats: 1) a preference test, 2) digestibility, ME, and fecal and urinary characteristics, and 3) postprandial plasma glycemia. Twelve healthy adult female cats were randomly distributed among 4 treatments consisting of a basal diet (4,090 kcal ME/kg DM, 32% CP, 11% fat, 2.3% crude fiber, and 7.0% ash) and 3 diets with varying percentages of glycerol, made by replacing the basal diet with 2.5, 5.0, and 10.0% purified glycerol (99.5%). The inclusion of glycerol proportionally reduced ( < 0.05) water activity in the diets. The preference test was conducted by observing the contrast between the basal diet and the 5.0% and 10% glycerol diets. Cats did not show a preference for any diet in particular ( > 0.05). The digestibility assays showed that increasing dietary glycerol levels did not affect food intake or the apparent total tract digestibility of macronutrients and energy ( > 0.05). The inclusion of glycerol in the diets did not alter the stool moisture, fecal score, or urine volume. However, glycerol was detected in urine when it was incorporated into the diet at 10%. Glycemia increased up to 900 min following the first meal after the fasting period with no difference between treatments, even when the means were adjusted for food intake. The blood glucose area under the curve also showed no significant difference between treatments ( > 0.05). Cats accepted glycerol under the conditions of the study, and its nutritional value was determined as it has been done for other species. The ME of glycerol for adult cats was estimated to be 3,185 kcal/kg DM. Supplementing the diets of the cats with 10% glycerol may exceed their capacity to metabolize glycerol, possibly leading to urinary excretions.

Energy values of canola meal, cottonseed meal, bakery meal, and peanut flour meal for broiler chickens determined using the regression method

The energy values of canola meal (CM), cottonseed meal (CSM), bakery meal (BM), and peanut flour meal (PFM) for broiler chickens were determined in 2 experiments with Ross 708 broiler chickens from d 21 to 28 posthatch. The birds were fed a standard broiler starter diet from d 0 to 21 posthatch. In each experiment, 320 birds were grouped by weight into 8 blocks of 5 cages with 8 birds per cage and assigned to 5 diets. Each experiment used a corn-soybean meal reference diet and 4 test diets in which test ingredients partly replaced the energy sources in the reference diet. The test diets in Exp. 1 consisted of 125 g CM, 250 g CM, 100 g CSM, or 200 g CSM/kg. In Exp. 2, the test diets consisted of 200 g BM, 400 g BM, 100 g PFM, or 200 g PFM/kg. The ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected metabolizable energy (ME_n) of all the test ingredients were determined by the regression method. The DM of CM, CSM, BM and PFM were 883, 878, 878, and 964 g/kg, respectively and the respective gross energies (GE) were 4,143, 4,237, 4,060, and 5,783 kcal/kg DM. In Exp. 1, the IDE were 2,132 and 2,197 kcal/kg DM for CM and CSM, respectively. The ME were 2,286 and 2,568 kcal/kg DM for CM and CSM, respectively. The ME_n were 1,931 kcal/kg DM for CM and 2,078 kcal/ kg DM for CSM. In Exp. 2, IDE values were 3,412 kcal/kg DM for BM and 4,801 kcal/kg DM for PFM; ME values were 3,176 and 4,601 kcal/kg DM for BM and PFM, respectively, and the ME_n values were 3,093 kcal/kg DM for BM and 4,112 kcal/kg DM for PFM. In conclusion, the current study showed that chickens can utilize a considerable amount of energy from these 4 ingredients, and also provided the energy values of CM, CSM, BM and PFM for broiler chickens.

Effects of wheat distillers dried grains with solubles with or without protease and β-mannanase on the performance of turkey hen poults

Expansion in bioethanol production has resulted in distillers dried grains with solubles (DDGS) being readily available as a major protein source in the poultry industry. Two experiments were conducted to investigate effects of wheat DDGS (wDDGS) and enzyme on nutrient digestibility and performance of turkey hen poults (7 to 21 d). Two starter diets (0 or 30% wDDGS) were formulated to meet or exceed the nutrient requirements for Hybrid Converter female turkeys. These diets were then mixed in different proportions to obtain 2 additional wDDGS inclusion levels (10 and 20%). In Experiment 1, 0 and 30% wDDGS diets were each subdivided into 3 portions and supplemented with no enzyme (E-), protease (P+; 0.125 g/kg) or β-mannanase (M+; 0.5 g/kg). A total of 144, 7-day-old poults were randomly distributed in groups of 4 in 6 replicate cages per treatment. There were no significant main effects or interactions on feed intake from 7 to 21 d. However, a positive (P<0.05) effect of 30% wDDGS was shown for weight gain and gain:feed. A significant interaction on nitrogen retention (NR) was found between enzymes and wDDGS level. There were significant main effects and interactions on the AME of the diets. The AME was higher (P<0.05) for 30% compared to 0% wDDGS. Supplementation of P+ decreased (P<0.05) AME for 0% diets as compared to 30% diets and vice versa for M+. In Experiment 2, 7-day-old poults (4 birds per 6 replications per treatment) were fed 4 levels of wDDGS (0, 10, 20, and 30%) with no enzyme. A linear (P<0.01) response was found for gain:feed with 30% wDDGS having a better response. Quadratic (P<0.01) responses were also found for NR and AME; both were highest for 10% wDDGS diets. In summary, no beneficial effects of P+ or M+ were demonstrated in diets containing 30% wDDGS. Wheat DDGS is a valuable energy source and as high as 30% can be incorporated in turkey hen poults (7 to 21 d) diets.

Evaluation of inclusion level of wheat distillers dried grains with solubles with and without protease or β-mannanase on performance and water intake of turkey hens

It is becoming a common practice to use higher levels of wheat distillers dried grains with solubles (wDDGS) in poultry diets. The objective of this study was to determine the effects of level of inclusion of wDDGS with or without enzyme (E-, i.e., wDDGSE-) supplementation on performance and water consumption of turkey hens (0 to 72 d). Two diets (0 or 30% wDDGS) were formulated to meet the nutrient requirements of Hybrid Converter turkeys. Diets (0 or 30% wDDGS; starter, grower, and finisher) were then blended to obtain a different level of inclusion (15%) of wDDGS. The 30% wDDGS diet was divided into 3 fractions and 2 fractions supplemented with either protease (P+, i.e., wDDGSP+; 0.126 g/kg) or β-mannanase (M+, i.e., wDDGSM+; 0.05 g/kg). All 5 diets were fed ad libitum as mash. The 700 0-d turkey hens were randomly allocated into groups of 35 birds per replicate with 4 replicate floor pens per treatment, in a completely randomized design. Water consumption per pen was recorded beginning at 7 d. There was no effect of dietary treatment on feed intake. BW of turkey hens (52 d; grower) was significantly higher for 30% wDDGSP+ as compared to 0% wDDGSE- or 15% wDDGSE- diets; but was not different from 30% wDDGSE- or 30% wDDGSM+ diets. FCR (P < 0.01; 28 to 52 d), and total FCR (P < 0.05; 0 to 72 d) was significantly improved for birds fed 15 or 30% wDDGS regardless of enzyme treatment compared to 0% wDDGSE-. Water intake (WI, in mL per bird per day) tended to be higher (P = 0.08) between 7 and 28 d for 30% wDDGSP+ diets compared to other treatments. Similarly, WI of birds fed 30% wDDGSP+ was higher (P < 0.05; 28 to 52 and 52 to 72 d) and total WI (P = 0.07; 7 to 72 d) tended to be higher than other treatments. This study is the first to report the impact of wDDGS on WI. As high as 30% wDDGS can be substituted in turkey hen diets. No effect of P+ or M+ at the inclusion level tested was found on performance.

Metabolizable energy content of wheat distillers' dried grains with solubles supplemented with or without a mixture of carbohydrases and protease for broilers and turkeys

In this study, 2 experiments were conducted to determine the AME and AMEn of wheat distillers' dried grains with solubles (DDGS) without or with supplementation of an enzyme mixture containing xylanase, amylase, and protease (XAP) in broilers and turkeys. One hundred twenty-six male Ross 308 broilers (Experiment 1) or 126 male BUT 10 turkeys (Experiment 2) were offered a nutrient-adequate diet from d 1 to 14. On d 14, birds in each experiment were allocated to 6 treatments consisting of 3 levels of wheat-DDGS (0, 300, or 600 g/kg) and 2 levels of XAP (0 or 250 mg/kg diet) in a randomized complete block design. The AME or AMEn content of wheat-DDGS was determined from the slope of regression of wheat-DDGS-associated energy intake (kilocalories) against wheat-DDGS intake (kilograms). In Experiment 1, wheat-DDGS inclusion in the diets linearly decreased (P<0.05) DM retention, AME, and AMEn, irrespective of XAP supplementation. The AME of wheat-DDGS without or with XAP for broilers was 3,587 or 3,700 kcal/kg DM, respectively, and AMEn was 3,356 and 3,459 kcal/kg DM for wheat-DDGS without and with XAP, respectively. In Experiment 2, wheat-DDGS inclusion in the diet linearly decreased (P<0.05) DM retention irrespective of XAP supplementation. Diet AME and AMEn linearly decreased (P<0.05) as the level of wheat-DDGS increased in the diets without added XAP, whereas there was no effect of increasing wheat-DDGS level on dietary AME or AMEn in the XAP-supplemented diets. The AME of wheat-DDGS without and with supplemental XAP for turkeys were 3,355 and 3,558 kcal/kg DM, respectively, and AMEn was 3,109 and 3,294 kcal/kg DM, respectively, for wheat-DDGS without and with XAP. Supplemental XAP increased (P>0.05) the AME and AMEn of wheat-DDGS for broilers and turkeys by up to 6%. It was concluded that wheat-DDGS is a valuable source of AME for broilers and turkeys.

Energy value of distillers dried grains with solubles and oilseed meals for pigs

The energy values of 3 distillers dried grains with solubles (DDGS) derived from corn, triticale, and sorghum and 3 oil seed meals including canola meal (CM), cottonseed meal (CSM), and sunflower meal (SFM) were determined in 2 experiments. For both of experiments, 24 crossbred barrows (initial BW: 28.0 ± 1.60 and 28.0 ± 2.0 kg for Exp. 1 and 2, respectively) were grouped by weight into 6 blocks and placed in a metabolism crate with 1 pig per crate. There were 4 diets in each experiment consisting of a corn-soybean meal reference diet and 3 test diets. The test diet consisted of each of 3 DDGS (Exp. 1) or 3 oil seed meals (Exp. 2) that partly replaced the energy yielding sources in the reference diet at 300 (Exp. 1) or 200 g/kg (Exp. 2) such that same ratios were maintained for all energy ingredients across all experimental diets. The DE, apparent ME (AME), and N-corrected AME (AMEn) of the test ingredients were determined by the difference method in 2 experiments each consisting of a 5-d adjustment and 5 d of total but separate collection of feces and urine. The respective DM or GE of corn DDGS, triticale DDGS, sorghum DDGS, CM, CSM, and SFM were 918, 927, 904, 912, 907, and 898 g/kg or 5,429, 5,298, 5,295, 5,063, 5,327, and 4,589 kcal/kg of DM. Addition of DDGS to reference diet in Exp. 1 decreased (P < 0.01) dietary DE, AME, and AMEn of the test diet. However, in Exp. 2, the respective energy values of the test diet were not affected by the addition of oil seed meals to reference diet except for SFM, which decreased (P < 0.01) the energy values. The respective DE, AME, and AMEn were 3,751, 3,559, and 3,361 kcal/kg of DM for corn DDGS, 3,720, 3,537, and 3,315 kcal/kg of DM for triticale DDGS, and 3,520, 3,355, and 3,228 kcal/kg of DM for sorghum DDGS. There was no difference in any of energy values among 3 DDGS evaluated in the current study. Furthermore, the respective DE, AME, and AMEn were 3,577, 3,428, and 3,087 kcal/kg of DM for CM and 3,281, 3,139, and 2,892 kcal/kg of DM for CSM, which were greater (P < 0.01) than those for SFM at 2,449, 2,253, and 2,071 kcal/kg of DM. In conclusion, the DE, AME, AMEn evaluated by difference method in the current experiment was not different among 3 DDGS derived from corn, triticale, and sorghum whereas the respective energy concentration was less in SFM than those in CM and CSM.

Linking ileal digestible phosphorus and bone mineralization in broiler chickens fed diets supplemented with phytase and highly soluble calcium

The objectives of this study were to determine the ileal digestibility of P in potassium phosphate, phytase-related ileal digestible P release, bone-mineralization-based ileal digestible P equivalency of phytase, and phytase-related efficiency of ileal digestible P utilization for bone mineralization in broiler chickens at 2 dietary concentrations of highly soluble Ca (HSC). Birds were sorted by BW at d 15 posthatch and assigned to 8 cages per diet with 8 birds per cage. Twelve diets were arranged in a 2 × 6 factorial of HSC at 5 or 6 g/kg and P supply treatment at 6 levels consisting of 4 added P levels (P from KH2PO4 added at 0, 0.7, 1.4, or 2.1 g/kg of diet) or 2 added phytase levels (500 or 1,000 phytase units). On d 24 posthatch, ileal digesta were collected for ileal P digestibility (IPD) determination and the left tibia was collected from the 4 heaviest birds in each cage for bone ash determination. Weight gain, G:F, and tibia ash were higher (P < 0.05) at 5 than at 6 g of HSC/kg. Added P from KH2PO4 or added phytase linearly increased (P < 0.001) weight gain, G:F, tibia ash, and IPD. The IPD of KH2PO4 derived from multiple linear regressions of digestible on total P intake for the diets without added phytase showed a reduction (P < 0.05) from 89.5 to 84.5% with increased HSC from 5 to 6 g/kg. Polynomial regressions of digestible P intake on phytase intake indicated that 1,000 units of added phytase released 1.701 or 1.561 g of digestible P in diets containing 5 or 6 g of added HSC/kg, respectively. Polynomial regressions of tibia ash on digestible P or phytase intake in diets containing 5 or 6 g of added HSC/kg at 1,000 phytase units gave digestible P equivalency of 1.487 or 1.448 g, respectively. Thus, phytase-related efficiency of ileal digestible P utilization for bone mineralization was 87.4 and 92.8% in diets containing 5 or 6 g of added HSC/kg, respectively.

True phosphorus digestibility of black-eyed pea and peanut flour without or with phytase supplementation in broiler chickens

Two studies were conducted to determine the true P digestibility (TPD) of black-eyed pea (BEP) and peanut flour (PNF) and the TPD response to phytase supplementation using the regression method. Sequential diets containing 115, 230, or 345 g of BEP/kg (experiment 1) and 115, 230, or 345 g of PNF/kg (experiment 2) without or with 1,000 units of phytase/kg were formulated. Chromic oxide was added to the diets at the rate of 5 g/kg as an indigestible marker. At 20 d posthatch in each study, 384 male broiler chickens (Ross 708) were weighed and allotted to the diets with 8 replicates of 8 birds each in a randomized complete block design. The birds had free access to the experimental diets until d 26 posthatch. In both studies, dietary P increase and phytase supplementation improved (P < 0.001) growth performance of the broiler chickens. There were linear increases (P < 0. 001) in ileal and excreta P output but a linear decrease (P < 0.001) in apparent P digestibility with an increase in dietary P levels. Phytase supplementation reduced (P < 0.001) ileal P and excreta P output and increased (P < 0.001) apparent P digestibility and retention. Apparent Ca digestibility was affected (P < 0.01) by P level and phytase addition in BEP and by P level (P < 0.05) in PNF. Apparent Ca retention in BEP increased (P < 0.05) with phytase addition. The TPD in the BEP increased (P < 0.01) from 29 without phytase to 83% with the addition of 1,000 units of phytase/kg. There was an increase (P < 0.01) in TPD of PNF from 67 without phytase to 75% with phytase supplementation. There was a corresponding increase (P < 0.01) in true P retention from 10% without phytase to 61% with phytase in birds on BEP diets and an equivalent increase (P < 0.01) in true P retention from 74% without phytase to 84% with phytase in birds that received the PNF diets.